The invention is in the first place intended for use on transport units which comprise coils of container blanks which in a filled state form flexible containers of a collapsible type. By container of collapsible type is meant a container with walls of a flexible plastic material, which are flexible and connected to each other to define a compartment, whose volume is dependent on the relative position of the walls. In its unfilled state, the container, and thus its container blank, is flat. The container blanks can be provided in a form of a coil, in which in a continuous web of container blanks is wound on a reel.
One example of a container of a collapsible type comprises three wall portions, of which two form opposite side walls and a third forms a bottom wall. The container blanks for this type of containers can be made, for instance, by folding a continuous web of material in the form of a W, after which the wall portions are joined along connecting portions to define a closed compartment. The container blanks can also be made by joining three continuous webs of material, one of which is folded in the form of a V to form the above-mentioned bottom wall. Regardless of method, this results in a continuous web of container blanks which, seen in the transverse direction of the web, have a first portion with a first number of layers (two walls) and a second portion with a second number of layers (four walls). When winding such a web on a reel, a coil is obtained, which in the first portion has a first density and in the second portion has a second density. This difference in density causes problems in handling, packing and transport of the coils.
Due to the difference in density, the coils cannot be stacked on top of each other without problems of instability and interleaving of the turns of two coils stacked on each other. Such instability and interleaving may cause “upsetting” and damage to the container blanks.
In order to prevent this, the coils are currently transported one by one in separate boxes. This results in unnecessary costs and also an environmental problem in the form of unnecessary packing.
The problem of upsetting and interleaving is particularly obvious if the transports, which is usually the case, occur over very long distances on frequently poor roads and with several reloadings. Damage entirely due to transport occurs and it is difficult to prove who caused the damage in transporting, and thus who is to pay the expenses of a claim. Due to the difficult burden of proof, the claim costs for transport damage must be paid by the supplier of packing material instead of the forwarding agent.
It will be appreciated that the above problem may to a certain extent also occur if the web of container blanks, seen in the transverse direction of the web, comprises the same number of layers. However, the problems of upsetting are less obvious.
There is thus a need for an improved method of packing this type of packing material.